Semiconductor integrated circuit

ABSTRACT

A semiconductor integrated circuit effectively makes use of wiring channels of wiring formed by a damascene method. When first cells are used, since the M 1  power source lines are laid out at positions spaced away from a boundary between the cells, the power source lines are not combined in laying out a semiconductor integrated circuit. As a result, the width of the power source lines is not changed. Accordingly, an interval between the line and a line which is arranged close to the line, determined in response to a line width of the lines, can satisfy a design rule; and, hence, the reduction of the wiring channels can be obviated, whereby the supply rate of the wiring channels can be enhanced, and, further, the integrity of a semiconductor chip can be enhanced.

This is a divisional application of U.S. application Ser. No.10/431,398, filed May 8, 2003 now U.S. Pat. No. 7,119,383, the entiredisclosure of which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a semiconductor integrated circuit(LSI) and a method of manufacture thereof; and, more particularly, theinvention relates to a semiconductor integrated circuit in which thereis an enhancement of the wiring density, as required by the nextgeneration of development, in which a semiconductor integrated circuithas a miniaturized structure. For example, the present invention relatesto a technique which is applicable in the formation of copper wiring bya damascene method in a semiconductor manufacturing process.

Recently, copper has been used as a wiring material for forming asemiconductor integrated circuit, since copper exhibits a low electricalresistivity, which is about ½ of the electrical resistivity of analuminum alloy. The use of copper makes it possible to realize speed-upand miniaturization of a semiconductor integrated circuit. The copperwiring is typically formed by a damascene method, by which it ispossible to overcome the problem that dry etching of copper isdifficult, for example. The damascene method is a technique in whichgrooves are formed in an insulation film; a conductive film, such as acopper film, which constitutes a wiring material, is embedded in thegrooves by plating, sputtering or the like; and, thereafter, the extracopper film outside the grooves is removed by chemical mechanicalpolishing (CMP), for example, so as to form conductive films in thegrooves. A method which embeds a conductive film in wiring grooves andconnection holes and forms wiring and plugs simultaneously is referredto as a dual damascene method, while a method which embeds a conductivefilm in wiring (or connection holes) and forms the wiring (or the plugs)is referred to as a single damascene method.

When the density of the wiring grooves or connection holes formed in theinsulation film differs depending on the regions of a substrate wherethey are located, the quantity of the metal film to be removed by CMPdiffers between the dense regions and the coarse regions. For example,in the dense regions, a larger quantity of metal film is embedded in thewiring grooves or the wiring holes than is similarly embedded in thecoarse regions; and, hence, the quantity of metal to be removed by CMPis increased in the dense regions, while the quantity of metal to beremoved by CMP is decreased in the coarse regions. As a result, therearises a phenomenon in which the insulation film which remains betweenregions of the substrate differ in film thickness. This phenomenon isreferred to as “erosion”. Further, the metal film and the insulationfilm (for example, a silicon oxide film) largely differ in the polishingspeed thereof when using the CMP method; and, hence, there arises aphenomenon in which the metal portions (portions such as wiring groovesor connection holes) are excessively polished. This phenomenon isreferred to as “dishing”. Japanese Unexamined Patent Publication2000-3912 describes that it is necessary to hold the wiring occupyingrate to equal to or less than a specific value to prevent such erosionor dishing.

For example, there is a design rule which indicates that a minimum linewidth is 0.2 μm and the minimum line interval is 0.2 μm; so that, whenlines having the minimum width are arranged at the minimum line intervalwithout gaps, the wiring occupying rate becomes 50%. However, in anactual LSI, there is no possibility that the lines will be arranged insuch a perfect manner; and, hence, in actual manufacturing practice, thewiring occupying rate is not more than 30%, for example, in many cases.

However, to consider a case in which a width of the line is set to 0.4μm, which is twice as large as the minimum line width, when lines havingsuch a line width are arranged at the minimum line interval of 0.2 μm,the line occupying rate is increased to 67%. This line occupying rate isremarkably high compared to the average wiring occupying rate of 30%,and, hence, such an increase of the line width is not desirable from theviewpoint of prevention of erosion and dishing.

Here, in a case in which the line interval corresponding to these widelines is set to 0.4 μm, the wiring occupying rate becomes 50% andapproaches the average wiring occupying rate, and, hence, it is possibleto obtain a preferable effect from the viewpoint of prevention oferosion and dishing.

Further, with respect to the wiring LSI of nowadays, an auto routingtechnique using DA (Design Automation) is usually used. Here, since thepositions where lines can be arranged (wiring channels) are arranged byusing a sum (basic pitch) of the minimum line width and the minimum lineinterval that is allowable as a reference based on a design rule, it isdesirable to determine the line width and the line interval of the widelines such that they conform to values which are an integer times aslarge as the basic pitch.

According to the latest miniaturized design rule, the difference betweenthe locally high wiring occupying rate and the average wiring occupyingrate, that is, an allowable wiring occupying rate, is becoming narrow.This tendency is particularly remarkable in the case of copper wiringusing a damascene method. As a result, in the latest miniaturized designrule, the line width value which can be arranged with the minimum linewidth is becoming narrower compared to the conventional line widthvalue.

SUMMARY OF THE INVENTION

The above-mentioned design (layout) of a semiconductor integratedcircuit device can be performed by selectively arranging cells, whichare preliminary laid out at a work station or the like and are stored asa library. Each cell includes power source lines and signal lines. Thepower source lines are, for example, arranged at a peripheral portion ofthe cell in the vertical direction (in the direction orthogonal to theextending direction of the power source lines) and the line widththereof is usually set to be wider than the line width of the signallines. Wiring channels are arranged between a pair of power source lines(Vdd, Vss) of the cell. The above-mentioned power source lines areconfigured such that, when a plurality of cells are arranged, the powersource lines of the neighboring cells in the vertical direction areconnected to each other, and the line width of the lines in the verticaldirection is widened so as to reduce the resistance of the power sourcelines. Accordingly, in a case in which a design rule is set such thatthe greater the line width of the lines, the wider will be the lineinterval between the line and another line which is arranged close tothe line in the vertical direction, although the design rule issatisfied when the single cell is laid out, at the time of laying out asemiconductor integrated circuit using the cells, the zone of the linewidth of the power source lines is increased, so that the design rule isnot satisfied. Accordingly, in laying out the semiconductor integratedcircuit, when the line width is increased by connecting the power sourcelines in the neighboring cells that are arranged in the verticaldirection, the interval between a line and another line which isarranged close to the line in the vertical direction is widened.Accordingly, the wiring channels which are closest to the power sourcelines in the vertical direction cannot be used. As a result, the supplyrate of the wiring channels is lowered, and it has been originally foundby the inventors of the present invention that the use of the wiringchannels, which constitute an upper layer, obstructs the enhancement ofthe integration of the semiconductor chip.

Further, as mentioned previously, with respect to the power sourcelines, when a plurality of cells are arranged, the power source lines ofthe neighboring cells in the vertical direction are connected to eachother, and, hence, the line width of the power source lines is changed.Accordingly, although the design rule is satisfied when a single cell islaid out, there is a possibility that, at the time of laying out thesemiconductor integrated circuit using plural cells, the zone of theline width of the power source lines is increased, so that the designrule is not satisfied. For example, the inventors of the presentinvention have found that, when a design rule is set such that when theline width of the lines is increased, the line interval between a lineand another line arranged close to the line is widened in the verticaldirection, although the design rule is satisfied when a single cell islaid out, there is a possibility that the design rule will not besatisfied at the time of laying out a semiconductor integrated circuitusing plural cells. That is, in spite of the fact that the power sourcelines that are arranged close to each other in the vertical directionare connected to each other so that the line width section is increaseddue to an increase of the line width of the power source lines, sincethe interval between lines in the cell is fixed, the design rule is notsatisfied in this case.

Accordingly, it is an object of the present invention to provide atechnique which can more effectively make use of wiring channels.

It is another object of the present invention to provide a techniquewhich can obviate the creation of a design rule error at the time offorming cells.

The above-mentioned and other objects and novel features of the presentinvention will become more apparent from the following description andthe attached drawings.

To present a summary of typical aspects of the invention disclosed inthis specification, the following examples are set forth.

That is, according to a first aspect of the present invention, in asemiconductor integrated circuit in which a plurality of cells havingrespectively given functions are arranged, lines which are arranged inperipheral portions of the cells are laid out at positions spaced awayfrom a boundary between cells which are arranged close to each other.

In such a case, the lines which are arranged in peripheral portions ofthe cells are laid out at positions spaced away from the boundarybetween cells which are arranged close to each other; and, hence, apossibility that the line width is widened due to coupling of wide-widthlines in the cells arranged close to each other is eliminated. When theinterval between a wide-width line and a line which is disposed close tothe wide-width line is widened corresponding to a line width of thewide-width line, due to the design rule, there is a possibility that thenumber of wiring channels is reduced. However, by adopting a layout inwhich the lines arranged at the peripheral portions of the cells aredisposed at positions spaced away from the boundary between the cellswhich are arranged close to each other, it is possible to prevent theline width of the wide-width line from being widened; and, hence, it isunnecessary to reduce the number of wiring channels. Accordingly, theavailability rate of the wiring channels is increased.

Further, according to a second aspect of the present invention, in asemiconductor integrated circuit in which a plurality of cells havingrespectively given functions are arranged, the cell includes wide-widthlines that are arranged at the peripheral portion and narrow-width lineshaving a line width narrower than a line width of the wide-width lines,and the line interval between a wide-width line and a narrow-width linewhich is arranged close to the wide-width line is set to be wider thanthe minimum arrangement pitch of the narrow-width lines. Here, it ispossible to set the ratio between the width of the wide-width line andthe width of the narrow-width line to a value equal to or more than 1:2.

In such a constitution, the line interval between a wide-width line anda narrow-width line, which is arranged close to the wide-width line, isset to be wider than the minimum arrangement pitch of the narrow-widthlines. That is, the line interval is widened corresponding to the linewidth of the wide-width lines. Accordingly, it is possible to preventthe occurrence of an undesired increase of the wiring occupying rate, sothat erosion and dishing can be prevented, whereby the semiconductorintegrated circuit can exhibit favorable properties.

According to a third aspect of the present invention, in a semiconductorintegrated circuit which is formed on one semiconductor substrate suchthat the semiconductor integrated circuit includes a first region and asecond region which is different from the first region, a plurality offirst cells having respectively given functions are arranged in thefirst region, lines which are arranged on a peripheral portion arearranged at positions spaced away from boundaries of the first cells,which are arranged close to each other in accordance with a layout, aplurality of second cells having respectively given functions arearranged in the second region, the second cell includes wide-width linesarranged on the peripheral portion and narrow-width lines having a linewidth narrower than the line width of the wide-width lines, and a lineinterval between the wide-width line and the narrow-width line which isarranged close to the wide-width line is set to be wider than theminimum arrangement pitch of the narrow-width lines.

In such a constitution, when the semiconductor integrated circuitincludes a first region and a second region which differs from the firstregion, the first cells and the second cells can be used correspondingto the respective regions.

In the above-mentioned semiconductor integrated circuit, the first cellincludes a bridging portion which is capable of bridging between theneighboring wide-width lines of the first cell and other first cellsdisposed close to the first cell, and by making use of a fact that theprobability that the arranged cells are simultaneously operated is not100%, when one cell is not operated, a power source line of one cell isoperated as if the power source line is a power source line of anothercell, whereby the effective allowable current value can be increased.

Further, according to a third aspect of the present invention, in amethod of manufacture of a semiconductor integrated circuit, whichincludes a first step of laying out the semiconductor integrated circuitusing cells and a second step of laying out a semiconductor integratedcircuit based on layout information of the semiconductor integratedcircuit, lines arranged in peripheral portions of the cells are laid outat positions spaced away from the peripheries of the cells.

Due to such a constitution, the lines in the peripheral portions of thecells can be laid out at positions spaced away from the boundaries ofthe cells which are arranged close to each other, it is possible toobviate an increase of the line width caused by coupling of thewide-width lines of the cells that are arranged close to each other.When the wide-width lines of the neighboring cells are coupled and theline width is increased eventually, the lines of the peripheral portionsand the wiring channels which are arranged close to the lines cannot beused as auto routing channels due to the violation of the wiringinterval rule. On the contrary, in this case, by arranging the lines ofthe peripheral portions of the cells at positions spaced away from theboundaries of the cells which are arranged close to each other, the linewidth of the wide-width lines cannot be widened. Accordingly, it ispossible to obviate a situation in which the lines of the peripheralportions and the wiring channels arranged close to the lines cannot beused as auto routing channels, due to the violation of wiring intervalrule, whereby it is possible to effectively utilize the wiring channels.

Further, according to a fourth aspect of the present invention, thewidth of power source lines arranged at the peripheral portions of thecells is preliminarily set to a large width, such that the width of thepower source lines is equivalent to a zone of the combined width of thepower source line formed by arranging a plurality of cells close to eachother in the first step. According to the layout which uses such cells,by setting the width of wide-width lines that are arranged at theperipheral portions of the cells to a width that is equivalent to thezone of the width of the power source lines, which are combined byarranging a plurality of cells close to each other in the first step,the use of wiring channels that are arranged close to the power sourcelines as lines is prohibited at the stage of the cells. Accordingly, itis possible to set an interval between the power source line and thenarrow-width line which is arranged close to the power source line thatis wider than the minimum arrangement pitch of the narrow-width lines.Since the interval between a power source line and a narrow-width linewhich is arranged close to the power source line is set to be wider thanthe minimum arrangement pitch of the narrow-width lines, it is possibleto make the distance between the power source line and the narrow-widthline, which is arranged close to the power source line, conform to thewiring rule when they are laid out on the semiconductor integratedcircuit at the stage of cells, whereby the violation of the design rulewhich may be revealed for the first time at the time of laying out thesemiconductor integrated circuit can be obviated at the stage of formingthe cells.

According to another aspect of the present invention, there is provideda method of manufacture of a semiconductor integrated circuit, includinga first step of laying out the semiconductor integrated circuit usingcells and a second step of forming the semiconductor integrated circuitbased on layout information of the semiconductor integrated circuit,wherein the cell includes first cells, in each of which a line in aperipheral portion of the cell is laid out at a position spaced awayfrom a periphery of the basic cell, and second cells in each of whichthe width of a wide-width line arranged at the cell is set to a valueequivalent to a zone of width of a power source line, which is formed bycombination by arranging a plurality of cells close to each other.

Further, the above-mentioned second step may include a metal lineforming treatment in which groove forming is applied to an insulationfilm, a wiring material is embedded into the grooves, and, thereafter,extra thin film outside the grooves is removed, thus forming lines bythe damascene method.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic plan view showing an example of theconstitution of first cells used in the layout of a semiconductorintegrated circuit according to the present invention.

FIG. 2 is a diagrammatic plan view showing an arrangement of the firstcells.

FIG. 3 is a diagrammatic plan view showing an arrangement of the cellswhich constitute an object to be compared with the first cells.

FIG. 4 is a diagram showing an example of the constitution of a firstcell.

FIG. 5 is a diagram showing an example of the constitution of the firstcell.

FIG. 6 is a diagram showing an example of the constitution of the firstcell.

FIG. 7 is a cross-sectional view as seen along line A-B in FIGS. 4, 5and 6.

FIG. 8 is a schematic circuit diagram showing the circuit constitutionof the first cell.

FIG. 9 is a diagrammatic plan view showing an example of the mainconstitution of a second cell used in a layout of the semiconductorintegrated circuit according to the present invention.

FIG. 10 is a diagrammatic plan view showing an arrangement of the secondcells.

FIG. 11 is a diagrammatic plan view showing an example of theconstitution of the second cell.

FIG. 12 is a cross-sectional view as seen along line C-D in FIG. 11.

FIG. 13 is a diagrammatic plan view of a semiconductor integratedcircuit including first cells and second cells.

FIG. 14 is diagrammatic plan view showing a modification of the firstcell.

FIG. 15 is diagrammatic plan view showing a specific example of wiringwhen the first cells are used.

FIG. 16 is a diagrammatic plan view showing a specific example of wiringwhen the second cells are used.

FIG. 17 is a table showing the relationship between a line space and anapplicable line width when the second cells are used.

FIG. 18 is a cross-sectional view as seen along line A-B in FIGS. 4, 5and 6, when the semiconductor integrated circuit corresponding to FIG. 7is manufactured using a damascene method.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A semiconductor integrated circuit (LSI) manufactured by the damascenemethod according to the present invention is constituted, for example,of a desired circuit, such as a logic circuit, which is formed byarranging cells (also referred to as “basic cells” or “unit cells”)corresponding to logic gates, such as inverter circuits (INV), NANDcircuits (NAND), flip-flop circuits (FF), NOR circuits (NOR) or thelike, on a semiconductor chip in a matrix array. That is, the cells areformed on the chip, and cells are connected to each other by lines so asto form a desired circuit. With respect to a power source (Vdd) and aground line (Vss), any one of these cells is preliminarily set tosatisfy the needed electrical characteristics. In this manner, by merelygenerating a master pattern relating to the wiring, it is possible toform various kinds of LSIs.

A process of manufacture of an LSI includes a first step in which alayout of the semiconductor integrated circuit is performed using thecells and a second step in which the semiconductor integrated circuit isformed based on layout information of the semiconductor integratedcircuit. In the first step, using a computer system, such as a workstation (not shown in the drawing), a layout tool, such as a layouteditor, is operated. The cells corresponding to the logic gates, such asthe inverter circuits (INV), the AND circuits, the NOR circuits or thelike, are prepared as a library.

The second step includes, for example, a patterning step in whichetching is performed using a mask to effect a photolithography techniquebased on the layout information, a step in which ion implantation ofimpurities is performed using a mask, a step in which a conductive filmis formed by stacking, a chemical mechanical polishing step and thelike.

FIG. 1 shows the essential constitution of the first cell used in thelayout of the semiconductor integrated circuit.

The size of the first cell 10 (hereinafter simply referred to as “cell10”) is determined by a quadrangular-shaped frame 103. Numeral 101indicates a high-potential-side (Vdd) power source line, numeral 102indicates a low-potential-side (Vss) power source line, numeral 104indicates channel positions (also referred to as “wiring channels” or“channels”) which can be used in auto routing on a first metal line (M1)layer. The first cell 10 is configured such that terminals of the cellare arranged on the usable channel positions 104 and the auto routingcan be performed after auto placement of the first cell 10 in the workstation. When the cell 10 is arranged or placed in the work station,lines are arranged on the usable wiring channel positions 104 and theterminals of the cells 10 are connected by lines. Here, other lineswhich connect terminals of other cells may pass over these channelpositions 104 of the cell 10.

Here, in the cell 10 shown in FIG. 1, the high-potential-side powersource lines 101 and the low-potential-side power source lines 102,which constitute lines on the peripheral portions of the cell 10, arearranged along the peripheries of the cell 10. That is, these powersource lines 101, 102 are arranged at positions spaced away from theperipheries of the cell 10 by the minimum arrangement pitch of thenarrow width lines. Here, the narrow width lines are lines having awidth narrower than the width of the power source lines, and theyusually correspond to the signal lines, and the minimum arrangementpitch corresponds to the wiring channel positions 104. The channelpositions 104 are used at the time of the laying out (auto placement androuting) of the semiconductor integrated circuit in the first step. Thatis, the channel positions 104 are not formed as physical structures inthe manufactured semiconductor integrated circuit device.

FIG. 4 shows an example of the arrangement of diffusion layers(semiconductor regions), gate electrodes, and the contact holes in theabove-mentioned cell 10.

Numeral 120 indicates the diffusion layers which constitute source/drainregions of a p-channel type MOS transistor, which are formed in n-typewell regions. Numeral 121 indicates the diffusion layers whichconstitute source/drain regions of an n-channel type MOS transistor,which are formed in p-type well regions. Numeral 122 indicates an n-typewell power-supply diffusion layer of the p-channel type MOS transistor120, and it is formed such that the diffusion layer 122 extends in theextending direction of the power source lines 101, 102 for reducing theresistance of the n-type well regions. Numeral 123 indicates a p-typewell power-supply diffusion layer of the n-channel type MOS transistor121, and it is formed such that the diffusion layer 123 extends in theextending direction of the power source lines 101, 102 for reducing theresistance of the p-type well region. Numeral 128 indicates contactholes (connection holes) for connecting the diffusion layers, the gateelectrode 124 of the MOS transistor and a metal line (MO), whichconstitutes an upper layer. A gate electrode 124 of the MOS transistoris formed on the well region by way of a gate insulation film (not shownin the drawing). Here, the gate electrode 124 of the p-channel type MOStransistor 120 and the gate electrode 124 of the n-channel type MOStransistor 121 are integrally formed. Further, on the diffusion layers120, 121, 122 and 123, silicide layers, for example, are respectivelyformed for reducing the resistance, while plugs are formed in thecontact holes, for example.

FIG. 5 shows an example of the arrangement of the inner wiring layersand through holes (connection holes) in the above-mentioned cell 10. Theinner wiring layers are formed of metal lines (M0) made of tungsten (W)or copper (Cu), for example, which are manufactured by the damascenemethod. Plugs made of tungsten (W), copper (Cu) or the like are formedinside the through holes (connection holes) and are manufactured by thedamascene method. The plugs are formed inside the through holes.

Numerals 141 to 145 indicate cell inside-connection wiring layers of theMOS transistor; numerals 146 and 147 indicate cell inner wiring layersfor power source connection of the MOS transistor; and numeral 148indicates a through hole for cell inside-connection wiring layers of theMOS transistor. The wiring layers (M0, M1), which constitute differentlayers, are connected to each other via the through holes.

In FIG. 6, terminal layers in the cell 10, which are constituted of thefirst metal (M1) wiring layers, wiring layers which are connected to theterminal layers, and the lines and power-source wiring layers which passabove the cell are illustrated. The terminal layers, the wiring layers,the lines, and the power source wiring layers are made of a metalmaterial, such as tungsten (W) or copper (Cu), and they are manufacturedby the damascene method. Here, the terminal layers, the wiring layers,the lines and plugs in the through holes may be manufactured by the dualdamascene method.

Numerals 151 to 154 indicate first metal (M1) line terminal layers;numeral 155 indicates a M1 wiring layer; numeral 156 to 159 indicate M1wiring layers, which are connected to terminal of the cells; numerals101-2(Vdd) and 101-2(Vss) indicate M1 power source wiring layers (Vdd,Vss) of the cell 10; and numerals 101-1(Vdd) and 102-3(Vss) indicate M1power source wiring layers of the cells 10-1, 10-3, which are arrangedclose to each other in the vertical direction (direction orthogonal tothe extending direction of the power source wiring layers).

Numeral 104 indicates the wiring channels (channel positions), which areformed between the M1 power source wiring layers 101-2, 102-2 of thecell 10-2. The M1 line terminal layer, the M1 wiring layer which passesover the cell and the M1 wiring layer which is connected to the terminalof the cell are arranged above the wiring channels 104 that are disposedbetween the M1 power source wiring layers 101-2, 102-2 of the cell 10,and they are connected to another cell arranged remotely in theleft-and-right direction (extending direction of the power source wiringlayer) of the cell 10-2 (10) by way of the M1 terminal layer, the M1wiring layer and the M1 line; or, alternatively, they are connected toanother cell that is arranged remotely in the up-and-down direction, aswell as in the left-and-right direction, of the cell 10-2 (10) by way ofthe M1 wiring layer and the M1 line. In this manner, the M1 terminallayer, the M2 wiring layer and the M2 line constitute inter-cell lines,which electrically connect cells that are configured to be spaced apartfrom each other in the up-and-down direction, as well as in theleft-and-right direction.

FIG. 7 shows a cross section of the cell 10. This cross sectioncorresponds to a line segment A-B in FIG. 4, FIG. 5 and FIG. 6.

On a silicon substrate 71, an n-type well region 72 n and a p-type wellregion 72 p are formed. On the p-type well region 72 p, the p-typediffusion layer 120, which constitutes the source/drain region of thep-channel type MOS transistor, the n-type diffusion layer 121, whichconstitutes a source/drain region of the n-channel type MOS transistor,the n-type well power-supply diffusion layer 122 of the p-channel typeMOS transistor, and the p-type well power-supply diffusion layer 123 ofthe n-channel type MOS transistor are formed. Further, as will beexplained later in conjunction with FIG. 18, interlayer insulation films501, 502, which are formed of silicon oxide films or the like, areformed such that these films 501, 502 cover the diffusion layers 120 to123. In these interlayer insulation films 501, 502, the cellinside-connection wiring layers 141 to 147 of the MOS transistor and thethrough holes (plugs) 128 are formed. These components are manufacturedby the damascene method, for example. Then, interlayer insulation films503, 504, which are formed of silicon oxide films or the like, areformed such that these films 503, 504 cover the cell inside-connectionwiring layers 141 to 147 of the MOS transistor. In the interlayerinsulation films 503, 504, the M1 power source wiring layers 101-1,101-2,102-2, 102-3, the terminal layers, the wiring layers and lines 151to 159 are formed. These components are manufactured by the damascenemethod, for example.

Next, the steps carried out in forming the semiconductor integratedcircuit will be explained in conjunction with FIG. 18.

The cell inside-connection wiring layers 145, the cell inner wiringlayers 146,147 for power source connection, and the M1 power sourcewiring layers 101-1, 101-2, 102-2, 102-3 are formed using the damascenemethod, for example. The interlayer insulation film 501 is formed suchthat the interlayer insulation film 501 covers the gate electrode 124 ofthe MOS transistor, the diffusion layers 120, 121 of the MOS transistor,and the well power-supply diffusion layers 122, 123 of the MOStransistor. The interlayer insulation film 501 is formed such that, forexample, the oxide silicon film 501 is stacked by the CVD (ChemicalVapor Deposition) method; and, thereafter, the surface of the siliconoxide film 501 is polished by chemical mechanical polishing (CMP) sothat the surface is leveled.

Subsequently, a photo resist film (not shown in the drawing and simplyreferred to as “resist film” hereinafter) is formed on a silicon oxidefilm 501, for example, and the contact holes 128 are formed in the gateelectrode 124 of the MOS transistor, the diffusion layers 120, 121 ofthe MOS transistor and the well power-supply diffusion layers 122,123 ofthe MOS transistor by etching the oxide silicon film 501, using theresist film as a mask.

Then, on the silicon oxide film 501, including the inside of the contactholes 128, for example, a thin titanium nitride (TiN) film is formed asa barrier metal layer by the CVD method or the sputtering method; and,thereafter, for example, a tungsten (W) film is stacked on the titaniumnitride film to serve as a conductive film by the CVD method. Then, aTiN film and a W film outside the contact holes 128 are removed by theCMP method, for example, so as to form the plugs 129.

Subsequently, on the interlayer insulation film 501 and the plugs 129,the interlayer insulation film 502 is stacked by the CVD method, forexample. Thereafter, the interlayer insulation film 502 is leveled bythe CMP method. Then, a resist film is formed on the interlayerinsulation film 502, and wiring grooves 150 are formed by etching thesilicon oxide film 502, using this resist film as a mask.

Then, on the interlayer insulation film 502, including the inside of thewiring grooves 150, for example, a thin TiN film is formed as a barriermetal layer by the CVD method or the sputtering method; and, thereafter,for example, a W film is stacked on the TiN film to serve as aconductive film by the CVD method.

Then, a TiN film and a W film outside the wiring grooves 150 are removedby the CMP method, for example, so as to form the cell inside-connectionwiring layer 145 and the cell inside wiring layers 146,147 for powersource connection, which are electrically connected with the plugs 129.

Subsequently, the interlayer insulation film 503 is formed on theinterlayer insulation film 502, the cell inside-connection wiring layer145 and the cell inside wiring layers 146, 147 for power sourceconnection by the CVD method, for example. Then, using steps similar tothe steps for forming the plugs 129, plugs 149, which are electricallyconnected with the cell inside wiring layer 145 and the cellinside-connection wiring layers 146, 147 for power source connection areformed on the interlayer insulation film 503.

Then, the interlayer insulation film 504 is formed on the interlayerinsulation film 503 and the plugs 149 by the CVD method, for example.Thereafter, using steps similar to the steps for forming the cellinside-connection wiring layer 145 and the cell inside wiring layers146, 147 for power source connection, the M1 power source wiring layers101-1, 101-2, 102-2, 102-03, which are electrically connected to theplugs 149, are formed on the interlayer insulation film 504.

Although a process for forming the wiring layers and the plugs using thedamascene method has been explained heretofore, these wiring layers andplugs also may be formed using the dual damascene method.

That is, the interlayer insulation films 501, 502 are stacked and thecontact holes 128 and the wiring grooves 150 are formed using the resistfilm as a mask. Thereafter, the barrier metal layers and the conductivefilm are embedded into the inside of the contact holes 128 and thewiring grooves 150, so that the plugs 129, the cell inside-connectionwiring layers 145 and the cell inside wiring layers 146, 147 for powersource connection may be formed.

In the same manner, after forming the interlayer insulation films 503,504, the plugs 149 and the M1 power source wiring layers 101-1, 101-2,102-2, 102-3 may be formed by the dual damascene method.

Further, although these wiring layers and the conductive films of theplugs are formed of tungsten (W), they may be formed of films havingcopper (Cu) as the main component. When a Cu film is used, the barriermetal layer is formed of a film made of Ti, Ta, TaN besides TiN or isformed of a laminated film constituted of these films.

FIG. 8 illustrates the circuit constitution of the cell 10 shown in FIG.4, FIG. 5 and FIG. 6.

As shown in FIG. 8, although there is no particular restriction on thecell 10, the cell 10 is constituted of four p-channel type MOStransistors 81 to 84 and four n-channel type MOS transistors 85 to 88.By combining these components, a three inputting NAND gate and aninverter are formed. That is, due to the combination of the p-channeltype MOS transistors 81 to 83 and the n-channel type MOS transistors 85to 87, a NAND gate is formed which operates according to NAND logic byfetching signals from the terminals 151 to 153, while due to thecombination of the p-channel type MOS transistor 84 and the n-channeltype MOS transistor 88, an inverter is formed which inverts the logic ofoutput signals of the above-mentioned three inputting NAND gates. Theoutput signal of the inverter is supplied through the terminal 154.

FIG. 2 shows a state in which, in the layout of the semiconductorintegrated circuit, in the vertical direction of a cell 10-2 that isconstituted in the same manner as the cell 10 shown in FIG. 1 (directionorthogonal to the extension direction of the power source wiringlayers), cells 10-1, 10-3 are arranged, which are constituted in thesame manner as the cell 10. In FIG. 2, some channels 104 and portions oflines are omitted from the cells 10-1 and 10-3.

As shown in FIG. 2, when the cells 10-1, 10-2 and 10-3 are arrangedclose to each other in the vertical direction, the high-potential-sidepower source lines M1 (Vdd) and the low-potential-side power sourcelines M1 (Vss) are laid out such that they are positioned so as to bespaced vertically away from the boundaries of the cells. That is, in thecells 10-1, 10-2 and 10-3, the high-potential-side power source linesM1(Vdd) and the low-potential-side power source lines M1 (Vss) in thecells 10-1, 10-2, 10-3, which constitute lines at the peripheralportions of the cells, are arranged at positions which are spaced awayfrom the peripheries of the cells in the vertical direction; and, hence,when these cells are arranged close to each other in the verticaldirection, as shown in FIG. 2, the M1 power source lines are laid out atpositions which are spaced away from the corresponding cell boundaries51, 52 in the vertical direction. Accordingly, in laying out thesemiconductor integrated circuit, the power source lines are notcombined between the cells 10-1 and 10-2, as well as between the cells10-2 and 10-3. For example, when the power source lines are arranged ina state such that they are not spaced away from the peripheries of thecells, as illustrated in FIG. 3, the power source lines are combinedbetween cells 9-1 and 9-2, as well as between cells 9-2 and 9-3, whichare arranged close to each other in the vertical direction. That is, apower source line 401 is formed by combining the power source line 401-1of the cell 9-1 and the power source line 401-2 of the cell 9-2, whichis arranged close to the cell 9-1, while a power source line 402 isformed by combining the power source line 402-2 of the cell 9-2 and thepower source line 402-3 of the cell 9-3, which is arranged close to thecell 9-2.

In this manner, since the power source lines of the cells which arearranged close to each other in the vertical direction are combined witheach other, the line width of the power source line becomes twice aslarge as the width of the line of a single cell. When a rule is set withrespect to an interval between a line and another line arranged close tothe line in accordance with the line width of the lines, the lineinterval is widened in accordance with the rule; and, hence, there is apossibility that, out of the wiring channels 104, the channels indicatedby numerals 161, 162, 163, 164 cannot be used as lines. When thesewiring channels cannot be used as lines, the supply rate of the wiringchannels in the first metal (M1) line is lowered, and this obstructs theenhancement of the integration of the semiconductor chip.

To the other hand, when the cells shown in FIG. 1 are used, since thepower source lines M1 are laid out at positions that are spaced awayfrom the boundaries of the cells, in laying out the semiconductorintegrated circuit, combination or joining of the power source linesamong the cells 10-1, 10-2, 10-3 shown in FIG. 2 does not occur. As aresult, the width of the power source lines is not changed. Accordingly,the design rule can be satisfied with respect to the interval between aline and another line which is arranged close to the line in accordancewith the line width of the line; and, hence, it is possible to preventthe reduction of the wiring channels, whereby it is possible to achievean enhancement of the supply rate of the wiring channels and also anenhancement of the integration of the semiconductor chip. That is, areduction of the number of wiring channels attributed to a design ruleviolation and a reduction of the integration based on a reduction of thenumber of wiring channels, which are revealed first of all in the layoutof the semiconductor integrated circuit, can be obviated at the time offorming the first cells in advance.

Here, a specific example of the line width shown in the above-mentionedcell 10 will be explained in conjunction with FIG. 15.

FIG. 15 shows a case in which the cells 10-1 and 10-2 are arranged closeto each other in the vertical direction. Numeral 51 indicates theboundary between the cells 10-1 and 10-2. In the cell 10-1, the M1channels are indicated by numerals 1, 2, 3 in order, moving away thecell boundary 51. In the cell 10-2, numerals -1, -2, -3 are indicated inorder, moving away from the cell boundary 51. Here, to the cell boundary51, “0” is allocated as the M1 channel for the sake of convenience. Theinterval of the M1 channels is defined as the sum of the minimum space Sand the minimum interval W of M1 (first layer metal line), and the sumis indicated by “P”.

Here, when the semiconductor integrated circuit is configured to be usedfrom the channel 2 in the upper-side cell 10-1 and from the channel -2in the lower-side cell 10-2, the M1 channels in the cells 10-1, 10-2 canbe effectively used.

Accordingly, to allow the M1 power source lines to be laid out atpositions that are spaced away from the boundary 51 between cells whichare arranged close to each other in the above-mentioned manner, thepower source lines in the peripheral portions of the cells 10-1, 10-2are laid out so as to be spaced away from the peripheries of the cells,and these cells are used in the layout of the semiconductor integratedcircuit. Further, the respective M1 power source lines of the cells thatare arranged close to each other are configured such that the linewidths assume the maximum values within a range of the given wiringrule.

The width of the M1 power source line is expressed by the followingequation.A=2×(W+S)−W/2−S−S/2=3W/2+S/2

For example, when the minimum interval W and the minimum space S are setsuch that W=0.2 μm, S=0.2 μm, the width of the M1 power source linebecomes 0.4 μm as expressed by the following equation.A=3×(0.2/2)+0.2/2=0.4

In this case, the ratio between the minimum line width (W) of the M1line and the M1 power source line width (A) is set to 1:2.

Now, a second cell, which is used in the layout of the above-mentionedsemiconductor integrated circuit, will be explained.

FIG. 9 shows an example of the constitution of the second cell used inthe layout of the semiconductor integrated circuit.

The size of the second cell 20 (hereinafter simply referred to as “cell20”) is determined on the basis of a quadrangular frame 203. In thedrawing, numeral 201 indicates a high-potential-side (Vdd) power sourceline; numeral 202 indicates a low-potential-side (Vss) power sourceline; and 204 indicates channel positions which can be used in autorouting in the first metal line (M1) layers. The cell 20 is configuredsuch that terminals are arranged on the usable channel positions 204 toenable connection by the auto routing after the auto placement of thecell 20 in the work station. When the cell 20 is placed in the workstation, the lines are placed at the usable channel positions 204 andthe terminals of the cell 10 are connected to the cell 20 by suchwiring. Here, other wiring, which connects terminals of other cells, maypass over the channel position 204 of the cell 20.

The cell height in the vertical direction (the direction orthogonal tothe extension direction of the power source wiring layers) of the cell20 (the width in the vertical direction of the frame 203) is configuredto be larger than the cell height in the vertical direction of the cell10 (the width in the vertical direction of the frame 103), and thenumber of wiring channels (channel positions) 204 of the cell 20 isconfigured to be larger than the number of the wiring channels 104 ofthe cell 10.

The cell 20 includes the M1 power source line, which is arranged at aperipheral portion of the cell, and narrow-width lines, which have anarrower line width than the power source lines, wherein the lineinterval between the M1 power source line and the narrow-width linewhich is arranged close to the M1 power source line is set to be widerthan the minimum arrangement pitch of the narrow-width lines. To be morespecific, the width of the wide-width line, which is arranged at theperipheral portion of the cell, is set to be slightly wider, such thatthe wide-width line projects from the frame 203 of the cell 20 andassumes a value equivalent to a zone of width of the M1 power sourceline, which is combined by arranging a plurality of cells close to eachother in the above-mentioned first step.

Although the circuit constitution or the like of the cell 20 is notparticularly limited, the cell 20 is configured to have the sameconstitution as the above-mentioned first cell 10 (FIG. 4 to FIG. 8).

FIG. 10 shows a state in which cells 20-1, 20-2 are arranged close toeach other in the vertical direction. The cells 20-1, 20-2 areconstituted in the same manner as the cell 20 shown in FIG. 9.

By arranging the cells 20-1, 20-2 close to each other in the verticaldirection, the M1 power source line 202-1 of the cell 20-1 and the M1power source line 202-2 of the cell 20-2, which is arranged close to thecell 20-1 in the vertical direction, are combined or joined whereby thewidth of the M1 power source line becomes twice as large as the width ofthe M1 power source line in the cell 20. Corresponding to the width ofthe combined power source line, the interval between the combined powersource line and the narrow-width line, which is arranged close to thecombined power source line, is set to be larger than the minimumarrangement pitch of the narrow-width lines (the arrangement pitchbetween the wiring channels 204-1, 204-2). That is, in the cell 20, thewidth of the large-width line, which is formed on the peripheral portionof the cell, is projected from the frame 203 of the cell 20 to assume aslightly wider value equivalent to the zone of the width of the combinedM1 power source lines, by arranging a plurality of cells close to eachother in the above-mentioned first step. Accordingly, out of the wiringchannels 204-1, 204-2 which are arranged close to the M1 power sourceline 201, the wiring channel indicated by numeral 205 cannot be used aswiring at the stage of the cell 20, whereby the interval between the M1power source lines 201, 202 and the narrow-width lines arranged close tothe M1 power source lines 201, 202 is set to be wider than a minimumarrangement pitch of the narrow-width line. In such cells 201, 202, bysetting the interval between the M1 power source line and thenarrow-width line, which is arranged close to the M1 power source linein the vertical direction, so that it is larger than the minimumarrangement pitch between the narrow-width lines, it is possible toensure the interval between the M1 power source line and thenarrow-width line, which are arranged close to each other in thevertical direction, at the stage of cells, such that the intervalconforms to the wiring rule when the semiconductor integrated circuit islaid out.

For example, in accordance with the prior arrangement, in a case inwhich the design rule is set such that the wider the width of the line,the wider will be the line interval between a line and another linewhich is arranged close to the line in the vertical direction, althoughat the time of laying out the single cell, the design rule is satisfied,at the time of laying out a semiconductor integrated circuit using thecells, the power source lines in the cells arranged close to each otherare combined with each other, so that the line width of the power sourceline is widened; whereby, even when the zone of the line width isincreased due to the broadening of the line width of the power sourceline, the interval between the lines in the cell is fixed, and, hence,there is a possibility that the design rule is not satisfied.

On the other hand, according to the layout using the above-mentionedcells 20-1, 20-2, in the cell 20, the width of the large-width line,which is formed on the peripheral portion of the cell, is projected fromthe frame 203 of the cell 20 to assume a slightly wider value equivalentto the zone of the width of the combined M1 power source lines byarranging a plurality of cells in the vertical direction close to eachother in the above-mentioned first step. Accordingly, the use of thewiring channel 205, which is arranged close to the M1 power source line201, is prohibited as the wiring in the stage of the cell 20.Accordingly, the interval between the M1 power source lines 201, 202 andthe narrow-width lines arranged close to the M1 power source lines 201,202 in the vertical direction is set to be wider than a minimumarrangement pitch of the narrow-width lines. In such cells 201, 202, bysetting the interval between the M1 power source line and thenarrow-width line, which is arranged close to the M1 power source linein the vertical direction, so that it is larger than the minimumarrangement pitch between the narrow-width lines, it is possible toensure the interval between the M1 power source line and thenarrow-width line, which are arranged close to each other in thevertical direction, such that the interval conforms to the wiring rulewhen the semiconductor integrated circuit is laid out, whereby a designrule violation which is revealed for the first time in the layout of thesemiconductor integrated circuit can be obviated at the time of formingthe second cell in advance.

That is, it is possible to reduce the resistance values of the M1 powersource lines 201, 202; and, at the same time, it is possible to ensurethe number of wiring channels 204 of the cell 20 and to make effectiveuse of these wiring channels 204. Further, it is possible to obviate adesign rule violation, and an increase of the design time incurred by adesign rule violation can be obviated at the time of forming the cell 20in advance.

FIG. 11 shows the arrangement of M1 terminal layers in the cell 20-2, M1wiring layers which are connected to these terminals, and the M1 lineswhich pass above the cell when the cells 20-1, 20-2, 20-3 are arrangedclose to each other in the vertical direction, and a cross section takenalong a line C-D in FIG. 11 is shown in FIG. 12.

Numerals 251 to 254 indicate the M1 terminal layers, and numerals 255,256 indicate the M1 wiring layers which pass above the cell, whereinthese layers are all formed on the wiring channels. Here, since thecells 20-1, 20-3 are also constituted in the same manner, theirconstitutions are omitted from FIG. 12.

Here, a specific example of the line widths in the above-mentioned cell20 will be explained in conjunction with FIG. 16 and FIG. 17.

FIG. 16 shows a case in which the cells 20-1, 20-2 are arranged close toeach other in the vertical direction. Numeral 61 indicates a boundarybetween the cells 20-1, 20-2. In the cell 20-1, the M1 channels areindicated by numerals 1, 2, 3, 4, 5, 6 in order, moving away from thecell boundary 61. In the cell 20-2, the M1 channels are indicated bynumerals -1, -2, -3, -4, -5, -6 in order, moving away from the cellboundary 61. Here, “0” is allocated to the cell boundary 61 as the M1channel for the sake of convenience.

In the drawing, the M1 channels are indicated by numerals. The intervalof M1 channels is defined as the sum of the minimum space S and theminimum interval W of M1 and is expressed as “P”. Further, in FIG. 17,the relationship between the line space and the applicable line width isshown.

Here, the width of the M1 power source line is set such that theallowable channels out of the M1 channels in the cell assume a statesimilar to a state at the time of the chip placement. The width of theM1 power source lines in the cells 20-1, 20-2 is expressed by thefollowing equation.B=4×P+W/2+W/2+α=4P+W+α

On the other hand, the width of the M1 power source lines at the time ofchip placement is expressed by the following equation.C=6×P+W/2+W/2=6P+W

The width of the M1 power source lines at the time of chip placement isexpressed as C=6P+W, and, hence, the required space defined based on thewidth of the M1 power source lines of the chip becomes S3 from FIG. 17.

On the other hand, the width of the M1 power source lines in the cell isexpressed as B=4P+W when α is expressed as α=0, and, hence, the requiredspace defined by the width of the M1 power source line in the cellassumes the value S2 from FIG. 17.

Accordingly, to realize a power source line width which demands therequired space corresponding to the chip power source line width at thetime of completion of the cell, it is necessary to set α to α>0, forexample, α=0.01.

FIG. 13 shows a semiconductor integrated circuit which is formed byusing the above-mentioned cell 10 and the above-mentioned cell 20.

In the semiconductor integrated circuit (chip) 301, a mask pattern isformed based on information which is produced in accordance with alayout using the cell 10 and the cell 20, and the semiconductorintegrated circuit 301 is formed by using this mask pattern. Here,although the invention is not particularly limited, the wiring of thesemiconductor integrated circuit is performed by the damascene method.That is, groove working is applied to an insulation film; copper whichconstitutes a wiring material is embedded in the grooves by a methodsuch as plating; and, thereafter, an extra copper thin film, which isdisposed outside the grooves, is removed by chemical mechanicalpolishing (CMP).

Although the invention is not particularly limited, the semiconductorintegrated circuit 301 includes an input/output circuit region 302, afirst region 303 and a second region 304. In the input/output circuitregion 302, there is a circuit which allows inputting/outputting ofsignals between the semiconductor integrated circuit 303 and theoutside. The first region 303 is constituted by using the first cells 10shown in FIG. 1, while the second region 304 is constituted of thesecond cells 20 shown in FIG. 9.

Although the invention is not particularly limited, the input/outputcircuit formed in the input/output circuit region 302 is constituted ofthe cells 10 and the cells 20.

That is, the gate width of the MOS transistor which constitutes the cell20 is configured to be larger than the gate width of the MOS transistorwhich constitutes the cell 10. Accordingly, the cell height in thevertical direction (direction orthogonal to the extension direction ofthe power source wiring layers) of the cell 20 (the width in thevertical direction of the frame 203) is configured to be larger than thecell height in the vertical direction of the cell 10 (width in thevertical direction of the frame 103) so that the number of wiringchannels (channel positions) 204 of the cell 20 is set to be larger thanthe number of the wiring channels 104 of the cell 10. Further, althoughthe invention is not particularly limited, the operating voltage (Vdd1)of the MOS transistor which constitutes the cell 20 is set higher thanthe operating voltage (Vdd2) of the MOS transistor which constitutes thecell 10, while the film thickness of the gate insulation film of the MOStransistor which constitutes the cell 20 may be set to be larger thanthe film thickness of the gate insulation film of the MOS transistorwhich constitutes the cell 10.

Here, the gate width, the cell height and the number of wiring channelsof the MOS transistor of the cell 20 that is used in the input/outputcircuit region 302 may be configured to differ from the gate width, thecell height and the number of wiring channels of the MOS transistor ofthe cell 20 that is used in the second region 304. Further, the gatewidth, the cell height and the number of wiring channels of the MOStransistor of the cell 10 that is used in the input/output circuitregion 302 may be configured to differ from the gate width, the cellheight and the number of wiring channels of the MOS transistor of thecell 10 that is used in the first region 303.

Due to such a constitution, the resistance values of the M1 power sourcelines 201, 202 of the cell 20 can be reduced; and, at the same time, itis possible to ensure the number of wiring channels 204 of the cells 10,20 and to make effective use of the wiring channels 204, whereby theintegration of the semiconductor integrated circuit 301 can be enhanced.Further, the period necessary for the series of steps from the designingto the manufacturing of the semiconductor integrated circuit 301 can beshortened.

In this manner, in the semiconductor integrated circuit shown in FIG.13, the first region and the second region, which differs from the firstregion, are formed on one semiconductor substrate. In the first region,a plurality of first cells, which have respective functions, arearranged in the first direction and in the second direction, which isorthogonal to the first direction, wherein the power source lines arearranged such that they extend in the first direction on the peripheralportion of the first cell, and the power source lines on the peripheralportion of the first cell are laid out at positions that are spaced awayfrom the boundary between the first cell and another cell which isarranged close to the cell in the second direction. Further, in thesecond region, a plurality of second cells, which have respectivefunctions, are arranged in the third direction (for example, one of theabove-mentioned first direction and the above-mentioned seconddirection) and the in the fourth direction, which is orthogonal to thethird direction, wherein the power source lines are arranged such thatthey extend in the third direction on the peripheral portion of thesecond cell, and the power source lines on the peripheral portion of thesecond cell are integrally formed with the power source lines of anothersecond cell, which is arranged close to the second cell in the fourthdirection.

Further, the above-mentioned second cell includes a wide-width line thatconstitutes the power source line, which is arranged at the peripheralportion of the second cell and extends in the third direction, andnarrow-width lines, which are arranged to extend in the third directionand have a narrower line width than the wide-width line.

Further, the power source lines and the narrow-width lines of the firstand second cells are formed by embedding conductive films into groovesformed in the insulation film.

FIG. 14 shows a modification of the first cell 10 used in the layout ofthe semiconductor integrated circuit shown in FIG. 1 and FIG. 13.

As shown in FIG. 14, with respect to the first cell 10 shown in FIG. 1and FIG. 13, between the power source line of the first cell 10 and thepower source line of another first cell 10, which is arranged close tothe first cell 10 in the vertical direction (the direction orthogonal tothe extending direction of the power source wiring layers), bridgingportions which are capable of bridging power supply lines may be formed.To be more specific, as shown in FIG. 14, in the first cells 10-1, 10-2which are arranged close to each other, bridging portions 171 are formedso as to bridge (integrally formed) the neighboring power source lines101-1, 101-2, while in the first cells 10-2, 10-3, which are arrangedclose to each other, the bridging portions 172 bridge (integrally form)the neighboring power source lines 102-2, 102-3 for every giveninterval. Although the invention is not particularly limited, thebridging portions 171, 172 may be formed by making use of the M1 wiringlayers. That is, at the time of forming the wiring grooves 101-1, 101-2,102-2, 102-3, grooves are also formed in the bridging portions 171, 172simultaneously, and conductive films are embedded into the wiringgrooves 101-1, 101-2, 102-2, 102-3 and the grooves formed in thebridging portions 171, 172 by CMP, whereby it is possible to form thebridging portions 171, 172 as well as the power source lines 101-1,101-2, 102-2, 102-3 using the same steps. Accordingly, the wiringgrooves 101-1, 101-2 and the bridging portions 171 are integrallyembedded with the conductive film, while the wiring grooves 102-2, 102-3and the bridging portions 172 are also integrally embedded with theconductive film.

With the provision of these bridging portions 171, 172, compared to thecase in which the Vdd power source lines 101-1, 101-2 and the Vss powersource lines 102-1, 102-3 are respectively present in a single form (thecase in which the bridging portions 172 are not present), the allowablecurrent value can be increased in the power source lines. That is, bymaking use of the phenomenon that the probability that the arrangedcells are operated simultaneously is not 100%, when one cell is notoperated, the power source line of the cell is operated as if the powersource line is that of another cell, which is disposed close to thecell, whereby the allowable electric current value can be effectivelyincreased.

Further, although the power source lines are constituted of thewide-width lines in the above-mentioned example, the wide-width linesmay be lines other than the power source lines.

In this manner, the power source lines of the first cells 10 which arearranged close to each other in the vertical direction (the seconddirection) in FIG. 1 and FIG. 13 include bridging portions which bridgethe power source lines.

According to the above-mentioned embodiment, the following advantageouseffects can be obtained.

(1) When the first cells 10-1, 10-2, 10-3 are used, since the M1 powersource lines are laid out to be spaced away from the boundaries of thecells, in laying out the semiconductor integrated circuit, the powersource lines are not combined among the cells 10-1, 10-2, 10-3. As aresult, the width of the power source lines is not changed. Accordingly,it is possible to satisfy the design rule with respect to the intervalbetween a line and another line arranged close to the line,corresponding to the line width of the line, and, hence, it is possibleto prevent the reduction of the number of wiring channels. Accordingly,the supply rate of the wiring channels can be enhanced, and, further,the integration of the semiconductor chip can be enhanced.

(2) According to the layout using the cells 20-1, 20-2, in the cell 20,by setting the width of the wide-width line arranged at the peripheralportion of the cell such that the width is slightly widened so as toproject from the frame 203 of the cell 20, whereby the width assumes avalue equivalent to the zone of the width of the combined M1 powersource line, which is formed by arranging a plurality of cells close toeach other in the first step, the wiring channel 205 which is arrangedclose to the M1 power source line 201 is prevented from being used asthe line at the stage of cell 20; and, hence, the interval between theM1 power source lines 201, 202 and the narrow-width lines arranged closeto the M1 power source lines 201, 202 can be set to be wider than theminimum arrangement pitch of the narrow-width lines. In this manner,since the interval between the M1 power source lines and thenarrow-width lines that are arranged close to the M1 power source lines201, 202 can be set to be wider than the minimum arrangement pitch ofthe narrow-width lines, it is possible to make the interval between theM1 power source lines and the narrow-width lines, which are arrangedclose to the M1 power source lines, conform to the wiring rule when thelayout is made with respect to the semiconductor integrated circuit atthe stage of cells, whereby the design rule violation which is revealedfor the first time in the layout of the semiconductor integrated circuitcan be obviated at the time of forming the second cell in advance.

(3) By taking the manner of operation and the advantageous effectsdescribed in the above-mentioned paragraphs (1) and (2) intoconsideration, it is possible to use either the first cell 10 or thesecond cell 20 in response to the ratio between the width of thenarrow-width lines (signal lines) and the wide-width lines (power sourcelines). For example, when the ratio between the width of thenarrow-width lines (signal lines) and the wide-width lines (power sourcelines) is less than 1:2, a priority is assigned to the enhancement ofthe supply rate of the wiring channels, so that the layout using thefirst cell 10 is adopted; while, when the ratio between the width of thenarrow-width lines (signal lines) and the wide-width lines (power sourcelines) is equal to or more than 1:2, a priority is assigned to obviatethe design rule violation, so that the layout using the second cell 20is adopted.

Although the invention has been explained specifically heretofore, it isneedless to say that the present invention is not limited to suchspecific constitutions, and various modifications can be made withoutdeparting from the gist of the present invention.

In the above-mentioned description, although the invention has beenexplained with respect to a semiconductor integrated circuit on whichthe wiring is formed using the damascene method, which constitutes theapplication field of the present invention, the present invention is notlimited to such a semiconductor integrated circuit.

The present invention is applicable provided that at least the cells areused.

To briefly recapitulate the advantageous effects obtained by typicalaspects of the invention disclosed in this specification, examplesthereof are as follows.

That is, since it is possible to lay out the lines on the peripheralportions of the cells at positions spaced away from the boundaries ofthe cells which are arranged close to each other, the phenomenon thatthe line width is widened due to the combination of the wide-width linesin the cells which are arranged close to each other, for example, can beobviated. When the line width is widened due to the combination of thewide-width lines in the cells which are arranged close to each other,the lines in the peripheral portion and the wiring channels which arearranged close to the lines in the peripheral portion violate the designrule on line interval, and, hence, they cannot be used as auto routingchannels. On the contrary, by laying out the lines in the peripheralportions of the cells at positions spaced away from the boundaries ofthe cells which are arranged close to each other, it is possible toprevent the line width of the wide-width lines from being widened; and,hence, the phenomenon that the lines in the peripheral portions and thewiring channels arranged close to the lines in the peripheral portionscannot be used as auto routing channels due to the violation of the lineinterval rule can be obviated, whereby the wiring channels can beeffectively used.

Further, the width of the power source line formed in the peripheralportion of the cell is preliminarily set to be wider such that the widthof the power source line assumes a value equivalent to the zone of thewidth of the power source line which is formed by combination when aplurality of cells are arranged close to each other in the first step.According to the layout adopting such cells, by setting the width of thewide-width line formed in the peripheral portion of the cell to bewider, such that the width of the wide-width line assumes a valueequivalent to the zone of the width of the power source line which isformed by combination when a plurality of cells are arranged close toeach other in the first step, the wiring channels which are arrangedclose to the power source line are prohibited from being used as theline at the stage of the cell, whereby the interval between the powersource line and the narrow-width line, which is arranged close to thepower source line, can be set to be wider than the minimum arrangementpitch of the narrow-width lines. Since the interval between the powersource line and the narrow-width line which is arranged close to thepower source line can be set to be wider than the minimum arrangementpitch of the narrow-width line, it is possible to ensure the intervalbetween the power source line and the narrow-width line, which arearranged close to each other, at the state of the cell, such that theinterval conforms to the wiring rule when the wiring is laid out in thesemiconductor integrated circuit, whereby the design rule violationwhich is revealed for the first time in the layout of the semiconductorintegrated circuit can be obviated at the time of forming the cells.

Effects of typical features of the invention disclosed in thisspecification are as follows.

Effective use of wiring channels of wiring is realized.

A design rule error is prevented at the time of forming cells.

1. A semiconductor integrated circuit which is formed on onesemiconductor substrate and which includes a first region and a secondregion, which is different from the first region, wherein, in the firstregion, a plurality of first cells having respectively given functionsare arranged in a first direction, as well as in a second directionorthogonal to the first direction, wherein power source lines extend inthe first direction and are arranged in the peripheral portions of thefirst cells, wherein the power source lines in the peripheral portionsof the first cell are laid out at positions spaced away in the seconddirection from a boundary defined between the first cell and anotherfirst cell which is arranged close to the first cell in the seconddirection, wherein, in the second region, a plurality of second cellshaving respective given functions are arranged in the third direction aswell as in a fourth direction orthogonal to the third direction, whereinpower source lines extend in the third direction and are arranged in theperipheral portions of the second cells, wherein the power source linein the peripheral portion of one second cell is configured to beintegrally formed with the power source line of another second cell,which is arranged close to the one second cell in the fourth direction,and wherein the power source lines are formed by embedding conductivefilm into grooves formed in an insulating film.
 2. A semiconductorintegrated circuit according to claim 1, wherein the power source linesof the first cells arranged too close to each other in the seconddirection include bridging portions which are bridgeable between thepower source lines.
 3. A seminconductor integrated circuit deviceaccording to claim 1, wherein the power source lines are comprised ofcopper.
 4. A semiconductor integrated circuit which is formed on onesemiconductor substrate and which includes a first region and a secondregion, which is different from the first region, wherein, in the firstregion, a plurality of first cells having respective given functions arearranged in a first direction as well as in a second directionorthogonal to the first direction, wherein power source lines extend inthe first direction and are arranged in the peripheral portions of thefirst cells, wherein the power source lines in the peripheral portionsof the first cell are laid out at positions away in the second directionfrom a boundary defined between the one first cell and another firstcell which is arranged close to the first cell in the second direction,wherein in the second region, a plurality of second cells havingrespective given functions are arranged in a third direction as well asin a fourth direction orthogonal to the third direction, wherein thesecond cell includes wide-width lines which constitute power sourcelines arranged in peripheral portions of a second cell and arranged toextend in the third direction and narrow-width lines having a narrowerline width than the wide-width lines and arranged to extend in the thirddirection, wherein the power source line in the peripheral portion of asecond cell is configured to be integrally formed with the power sourceline of another second cell, which is arranged close to the one secondcell in the fourth direction, and wherein the power source lines areformed by embedding conductive film into grooves formed in an insulatingfilm.
 5. A semiconductor integrated circuit acceding to claim 4, whereinthe power source lines of the first cells arranged too close to eachother in the second direction include bridging portions which arebridgeable between the power source lines.
 6. A semiconductor integratedcircuit device according to claim 4, wherein the power source lines arecomprised of copper.